This document provides an overview of Android for developers getting started with Android programming. It discusses what Android is, the history and versions of Android, the architecture and features of the Android operating system, popular Android devices, and Android's app marketplace. The key points are: Android is an open source, Linux-based OS acquired by Google; it has gone through many versions codenamed after desserts; the architecture includes the Linux kernel, libraries, runtime and framework; and it powers a wide range of devices led by smartphones.